1. Field of the Invention
This invention relates in general to detecting characteristics of hot gaseous plumes such as missile and jet engine exhaust, and in particular to means for identifying the object based upon the modulation within the plume.
2. Description of the Prior Art
Most military jets that are downed by an enemy are destroyed by missiles. The missiles may be either radar or infrared guided missiles. If the aircraft pilot detects the missile being fired at him, he can take counter measures. He can make tight maneuvers, and he could eject flares and metal chaff to confuse either heat or radar guided missiles.
The counter measures require that the pilot be able to detect the missile before it becomes too close for any counter measures to be taken. Once the missile is launched, the pilot has only about one second to detect it, and another two seconds to start the counter measures. Current systems do not provide adequate detection of the launching of a missile.
Modern aircraft are vulnerable to missiles because of active and passive missile guidance techniques. The missile can passively lock onto the aircraft plume, hot metal parts and/or aircraft emissions such as radar and radio. Actively, the missile can be guided to the airplane by its own radar or laser.
The aircraft is not now warned of the oncoming missile because radar warning techniques will give away the position of the aircraft. Present infrared technique are useless because of the extremely high number of heat sources in the battle field, each of which looks like a missile to existing infrared systems. There may be other aircraft in the area, including friendly aircraft which produce heat. Ground fire could also cause a false alarm. Even if detected, the pilot must learn of the fired missile early enough to begin his counter measures.